Pneumatic tool.



a. H. GILMAN. l PNEVUMATIC TGM.

APPLICATION FILED APR. 2; |909.

Patented July 27, 1915. j

zesses f GEORGE H. GELB/IAN, OF CLAREMONT, NEW HAMSHIR, ASSIGNOR, BY MESNE ASSIGN- MENTS, T SULLIVAN MACHINERY COMPANY, OF BGSTON, MASSrG-ITJ'SE'E'S,l A. I

CORPOB-,-TION GF MASSACHUSETTS.

, PNEUMATIC TOOL.

Lia-sere.

Application filed Apr12, 1.909. Serial No. 487,506.

' To all whom t may concern.'

ybodiment of my invention there Be it known that I, GEORGE H. GiLMaN, a citizen oic the United States, residing at Claremont, inthe county of Sullivan and Stat-e of New Hampshire, have invented an Improvement inPneumatic Tools, of which Athe following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to pneumatic tools, consisting more particularly, thouglinot eX- clusively, in the provision of means for se-v curing the easy and quiet operation of the tool while at the same time maintaining its high eiiiciency. t

My invention will be best understood by reference to the following description when taken in connection with the accompanying illustration of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings Figure 1 is an elevation in partial central section showing a han/d tool embodying 'one orm'ot my invention; Fig. 2 is a similar section, partly broken away and on a larger scale, such section being taken in a diierent plane to show other ports and passages; Fig. 3 is an enlarged section of the cushioning plate and adjacent ports; Figa shows in section a cushion plate of a modified construction; and Fig. 5 shows still another modification.

Referring to the shown, l have selectedfor illustration a pneumatic hammer drill oa type generally employed for stone working, although it is to be uny derstood'tliat my invention has application to tools of different construction than the one hereinshown and intended for use with other motive fluids than air and for 'other purposes than drilling.

The illustrated lform of tool is provided with a cylinder 1, which latter is embraced l'at'its rear endby the head block or casing 2 on which is mounted the handle 3 having the grasping portion 4. In the forward end of the-'cylinderthere is provided a chuck 5 through which passes the shank or head of the drill tool f6, the inner end thereof being positioned to receive the 4blows of the name mer4p`iston7 which reciprocates within the cylinder,

'pressure chamber.

drawings and to the einy The hammer piston is'actuated by `pressure Huid controlled by the pressure actuated valve 8, which herein is of the general type shown in the prior U.' S. Patent No.

902,288 granted to me 0ctober,27, 1908.-

tto be more fully referred to. The general operation of this type of valve is well understood. rhe pressure fluid is conducted to the tool from any suitable source (not shown) through the supply pipe 12 and through any suitable throttling device (also not shown) to the constant pressure chamber 13 at the rear of the valve block. The

val've chamber at its rear end communicatesI with the constant pressure chamber through an opening 14 of reduced cross" sectional i area. and the valve has a contracted-portionl 15 slidable in said opening; and constantly exposed to the working pressure uid in the constant pressure chamber. rlheva'lve block is provided with a .constantpressure groove 16 to which the working pressureisfconstantly admitted throughjone Orinore vlongitudinal passages 17, 'the` latter e'itei'iding from said groove rearwardly to the constant In the' rear position of the valve, working pressure is conducted from the pressure groove 16 to the forward end of the cylinder to return the piston by wavl of the circumferential valve'groove 17X to the .port

about the'circumferential groove ,17 X fon the valve to the' valve block groove 20 and thence forward through the longitudinal' passages 21. The latter are cut through the valve block 9 and the valve plate 10 and 18 (Fig. 2) and thence to the' lforward end of the cylinder through the enter a contracted chamber 22 formed' at the vend of the cylinder chamber in the plate 11, entrance to said chamber being had from said longitudinal passages through one or more inclined admission ports 23,. Exhaust is e'ected from the rearof the cyll nder, when the valve is in its rearward position, through the said ports Q3, longitudinal passages 21, the valve-block groove 20, the forward circumferential groovevel on `the valve and one or more transverseexhaust ports Q5 Q) which open laterallv from the valve,l chamber into the annular exhaustspace QG, which latter is formed between the casing i2 and the valve block 9. F rom .the forward endl of the c vli'nder exhaust takes place through the longitudinal exhaust passage QT (Fig. 1), which latter at its rear end opens into the said annular exhaust space QG and at its forward end iinto the chamber Q3 which surrounds the head of the tool. The said chamber is connected with t-he main cvlinder chamber through an opening Q0 of reduced cross section, lwhich opening the forward contracted portion 30 i lot' the piston hammer enters prior to striking the tool. vlVhen, therefore, the piston hammer is in its forward position, with the contracted'portion 30 within the opening 29,

the forward end-of the c vlinder chamber is cut olil from the exhaust chamber 28. On the rearward movement of the piston, how,-

ever, as soon as the contract-ed portion 30 has withdrawn from the opening Q9 the forsward end of the piston is conne-cted withthe exhaust through the said chamber 2 8' and longitudinal 'passages 27. The valve is reciprocated by dil'erentia pressure, being provided with means for intermittently applying pressure fluid to the forwardor'larger area of the valve to intermittently litt it against the constantV pres.- sure in the pressure chamber 13. To this .-end, the valve is constructed inthe form of a hollow shell, the interior ot which is par tially filled by the plug 31, the latter having the groove or passage 32 (Fig. 2)y formed in its side. connecting withA the intermittent p ssure passage rl`he pressurpassage 33 is connected with two ports 3st and opening into the cfylinder chamber at diff ferent points lengthwise the same, the port 3i being in substantiallyv the same plane as a second port 36, which latter is in constant communication with the constant pressure chamber 13 through the longitudinal passage 37 (see Fig. 1). lVhen the piston moves forward, the port 3st is. connected with the constant pressure port 36 by means of the reduced portion 38 on the piston. andthe valve is reversed by pressure admitted to the large area thereof from the constant pressure chamber. On the other hand, when the piston moves ba-:ikwuird pressure fluid is exhausted from the larger area of the valve by the piston uncoveringthe port 35 and connecting the latter to the exhaust through the chamber :23 and exhaust passage 2T. The port 35 is preferably, 'though not necessarily, so positioned that it is uncovered at about the saine time. Through the reciprocation vof the Valve and the transfer of pressure Ilnid through the described ports and passages, the hammer piston is caused to move reciprocatively within the cylinder and deliver its blows against the headof the tool Afrom the admission port neai the end of its stroke and to form a cushion by means of the pressure fluid trappedtherein,much/.of the vibration referred yto can be eliminated while still-maintaining a high working etliciencv for the tool,` providedr the valve is moved toadmit working pressure Huid to the said chamber before the latter is cut off fromthe admission ports, so thatthe vpiston acts to compress live or working pressure fluid. .In the construction shown in Figs 1` "2 and 3 such cushioning chamber is provided byinterposing the cushioning plate 11 with its contracted chamber Q2 between the valve chamber and the valve plate 10 4and providing upon the rear end ot' the piston the projecting member 3S of such a diameter that it is capable of entering the chamber 'Q2 near Vthe end of the rearward piston stroke and cutting oit communica-tion between the same and the space in the rear partof the main cylinder chamber which still remains between the front walls of the cushion plate and the main rear wall 39 of the piston.

Referring to Fig. f2, it will be seen that the ports are so arranged that prior to the entrance of the contracted portion 38 into the chamber 22 andthe closing of communication between the cushioning portion 40 of the cylinder chamber and the admission ports 23, the valve S has been thrown toits forward position to admit working pressure to the .rear of the piston. so that live or working pressure fluid as distinguished from exhaust fluid is trapped in the cushioning space.` lVith livepressure fiujvlil trapped in the cushion space 40, the piston is brought verse movement, the work done in compress-v ing the fluid is restored to the piston and the vtorest with little or no shock and, on itsl re-y macero -seen that the passages 21 are so arranged slightly modified over that shown in Fig. 3,

there being employed a cusl'iioning plate 4l wherein the central chamber 42 which receives the piston projection 38 is disconnect- -ed from the admission ports and itself'forms the cushioning chamber. T he admission ports 43 open directly from the longitudinal passages 2l into the rear end of the cylinder', ,l

so that the cushion is formed at the end of the projection 3S instead of against the main area 39 of the piston. u

In Fig. 5, have shown still another form vwherein the longitudinal passages 2l in the" valve plate l0 register with passa ges'44' in the cushion plate 45, and the latter with other .passages 46 formed in the cylinder walls, which passages enter the cylinder chamber laterally at a point suliiciently forward from the rear end of the chamber to permit the piston to overrun the same and form a cushion at the rear thereof. In each case it is of course understood that a port arrangement is adopted, as in Figs. 1 to 3, whereby I,the valve acts to admit working pressure to the cushion chamber prior to the cutting ofi ot the same from the cylinder admission ports.

In Fig. i, l have shown in connection with the exhaust ports an exhaust controlling' valve. Such valve comprises a valve member 4'? controlled by the cock or handle 48 and adapted to vary theextent of the port openingfrom the annular exhaust space 26 to the atmosphere, so that the exhaust may be more or less throttled or entirely cut off if desired. In connection with such exhaust valve, the tool 6 is preferably provided with an axial or other passage 49 leading from the head end to the Working edge of the tool, so that the exhaust fluid can pass from the chamber 28 to the cutting edge of the tool, and thereby he employed for clearing the cut of dust and cuttings. By closing the exhaust valve 47 more or less, the amount of exhaust iluid thus discharged 'through the tool may be controlled. l

While I have shown and described one specific form of my invention for purposes of illustration, it is to be understood that the same is not limited to the specific details shown'nor Ito theparticular form or arrangem'ent of parts, but thatextensive deviations may be madefrom the described form-without departing from the spirit of my invention. f

Having thus described my invention, what ll claim is:

l. A pressure fluid tool f comprising, in combination, a cylinder, a piston working therein, said cylinder having a cushioning chamber at one end thereof to which working fluid is admitted by said valve through a suitable admission port or ports, said piston ybeing suitably arranged to cut ofi' said chamber from said port near the end of its normal stroke to provide a cushion through the fluid trapped therein, and means to cause said valve to admit working pressure Huid prior and while said chamber is cut oil, thereby to cushion said piston against working pressure fluid.

2. A pneumatic tool having a cylinder, a hammer piston, a valve block with its yvalve chamber-and a valve therein at the rear of said cylinder and in alinement with lsaid piston, a cushion plate between the valve block and the end of the cylinder and presenting a contracted opening, a projection of reduced cross sectional area on the rear of the piston adapted to enter said opening adjacent the end of the normal stroke and close communication between the same and the main cylinder chamber, and means for moving the valve to admit pressure fluid to said cylinder end prior to the entrance of said projection into said opening.

A pneumatic tool hav-ing a cylinder l, a

piston hammer 7 valve 8, projection 38 of reduced cross sectional area, and cushion plate l1 with chamber 22 the valve moving means acting to open the rear of the cylinder to pressure fluid before and during the entrance of the projection within the cushion charn-A ber.

4. A pneumatic tool having a cylinder, a hammer piston, a valve at one end thereof, and said piston having an end projection of reduced cross sectional area and forming wo end )ressure areas for the iston the rear of the cylinder chamber vpresenting a contracted opening into which the said projection is adapted to enter adjacent the end of the normal stroke to close communication between the same and the rear of the cylinder and forming thereby a cushion at the rear of the cylinder, and means for moving the valve to admit pressure fluid to the rear end of the cylinder before the entrance of the projection into the said opening to cause the formation of the cushion on ylive pressure fluid, the admission passage or passages entering said contracted opening to continue the admission of pressure fluid against the end projection of the piston vduring the continuation of the said cushion.-

5. A pneumatic tool having a cylinder, a hammer piston, a valve at one end thereof and said piston having an end projection of reduced cross sectional area and forming two end pressure areas for the piston, the rear of the cylinder opening presenting a con` tracted opening' igto which thev said projection is adapted to enter adjacent the end of the normal stroke to close communication between the same and the rear of the cylinder and forming thereby a cushion; means formoving the valve to admit pressure Huid lto said cylinder-end' before the entrance oi the projection into the opening to eause'the ltol-mation of the cushion on live pressure fluid, the admission passage or passages being so locatedy as to continue the admission of pressure tiuid against one of said piston areas during the continuation of the cushion.

6. A pneumatic tool having a cylinder, a.

hammer piston, a valve, said c vlinder vhavof to which workingvluid is admitted by said valve through a suitable-admission port .j or ports, said hammer being suitably, formed to cut off said chamber' from said -port adjacent the end 'ot its normal stroke to prov ide a cushion 'through the fluid trapped therein, and means to move said valve to admit working pressure iuid prior tothe y ycutting off ot said chamber, thereby t0 -cushion the piston a fluid, said piston being provided with a 4pressure area against which pressure iuid 1s i: admitted cushion.

7. A -pneumatic tool having a cvlinder, a hammer piston, a valve block chamber and valve4 therein at the rear of said c vlmder and 1n alinement with said piston. a grasping handle at the rear ot said valve block, said 1cylinder having a cushioning; chamber atonc end thereotl to which wcking `tluid is admitted bv said valve thraigh a suitable admission port, said hammer being suitablv tormed to eut ofi' said chamber from said port adjacent the end ot its normal stroke to provide a cushion through the tluid trapped therein, and means to move said valve to admit working pressure fluid prior to 'the cutting ott1 of said chamber. therebv to cushion' the piston against 4working pressure Huid. said piston I being provided with a pressure area against which pressure iiuid is .admitted during the eontimlation of the cushion.

S. A pneumatic tool having a c \`"linder7l a hammer piston. a valve bloelt'with its in-g a cushioning chamber at one end there-v gainst working pressurey during the continuation of the duced cross sectional area on the rear ot the' 'piston adapted to enter said opening and close connnunieation between the' same and the main cylinder chamber, and means -for moving the valve to admit pressure fluid from said pressure space about .the sides of said valve through said passagesl to said cylinder end prior to the entrance oi. said projection into said opening.

' 9. A pneumatic tool having a cylinder` a hammer piston, a valve block with, its valve chamber and a valve therein at the rear of said evlinder and in alinemen'twith said pis? ton, tneans presenting angaxial Icontracted opening at the rear end ot said cylinder,

lsaid valve block having a constant pressureV hammer piston` a valve block with its valve" chamber and a valve therein at the rear otr said cylinder and in` alinement/ with said piston, means presenting a contracted opening at thel 'rear end oli said c vlinder. said valve block and said means having a passage or passages controlled ib v said valve leading from a pressure space at the rea'r ot said valve laterallvo't said valve'into communication lwith the rear end ot `said c vlindeix.' a projection ot 'reducer-l cross' sectional area on the rear ot the piston adaptedl to enter said opening and close communication between the same and the main c vlinder ehan'iber. andincans tor moving the valve to admit pressure fluid from said pressure-space through saidpasgaige to said cvlinder end prior to the entrance ol' .said projection into said opening'.

ll. A pressure fluid engine comprising. in combination. a evlindeiza piston working therein` a valve. said piston having an end projection ot' reduced cross-sectional areaand toi-'nung two end pressure areas tor the piston. .the lrear of' the cylinder: chamber presenting a contracted opening into whichsaid projection is adapted to enter adjacent the end ot the. normal stroke to e'los'ecommunication between the same' and the rear ol the evlin'dcr and torlning there-bv a cushion at.r the rear o t the,lejvlinder.l and means tor moving the valveto admitI pressure uid to the rear end of tlm-cylinderbetere the entrance 'of the projection `into the said opening 'to cause the formation of the loo cushion on live pressurejfluid, the admission passage or passages enterlng sald contracted opening to continue the admission of pressure fluid againstl the end projection.

of the piston lduring the ,continuation of said cushion.

12. A pressure lfluid engine compris1ng,lin combination, a cylinder, a piston working l "therein, a valve, said piston having an end projeetion of reducedcross-sectional area 1 and forming two end pressure areas for the piston, the rear of the cylinder opening presenting a contracted opening into which the said projection is adapted to enter adjacent the end. of the normal stroke tofclose -communication between the same and the rear r of the cylinder and'- forming thereby a cushion, means for moving the valve to admit'pressure Huid to; said cylinder end before the'entrance of the projection into the opening to causethe formation of the cushion on live pressure iiuid, the admission passage or passages being so located-as to continue4 the admlsslon of pressure fluid against one of said vpiston areas during 'the lcontinuation of the cushion.

13. Al pressure fluid engine comprising, in combination, a cylinder, Aa piston working therein, a valve, said gylinder having a cushioning chamber at one end thereof to which Working iuid is admitted by `said valve,

through a suitable lport or ports, said piston being suitably arranged to cut Oft' said cham# ber from said port adjacent the end-of its normal'stroke to provide a' cushion through the fluid trapped therein, and means to move said valve to admit'working pressure Huid prior to the cutting off of said chamber thereby to cushion 'the piston against Working pressure Huid, said piston being. pro- I vided'with a pressure area against which pressure iuid is admitted during the coni tinuation of the cushion.

14. A pressure IHuid tool oompr1-s1ng, inA

combination, a cylinder, a piston workmg therein, a'valve block Withl a valve chamber and valve therein, said cylinder having a cushioning chamber at onev end thereofto which working Huid is admitted by said valve through a suitable admission port, said piston being suitably arranged to cut o14 said chamber from said port adjacent the'endof itsl normal stroke to provide a cushion through the Huid trapped therein, and means to move'saidivalve to admit working pressurevfluid priorl to the cutting 0E of said chamberthereby to cushion the piston against working pressure fluid, said piston being provided with a pressure. area against which pressure Huid is admitted v during the 'continuation of the cushion. 

